Heat resistant pipe and method of manufacture thereof

ABSTRACT

A heat resistant pipe is formed from a composition comprising polyphenylene ether resin and polystyrene resin. Pipes made from this composition possess superior thermal and pressure resistance. Their impact resistance and thermal expansion characteristics permit them to be utilized advantageously in all environments and during all seasons with little risk of failure.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to Japanese Patent ApplicationNo. JP2001-269472, filed on Sep. 5, 2001, which is incorporated hereinin its entirety.

BACKGROUND

[0002] This disclosure relates to heat resistant pipe and a method ofmanufacture thereof.

[0003] Steel piping has traditionally been utilized to carry andtransmit water and other fluids. However, steel piping suffers from thedrawback that it is heavy and cumbersome. Its large mass generallycauses problems during manufacturing processes such as cutting, fitting,and the like. It also renders installation processes cumbersome andexpensive due to the large number of personnel required. Steel pipingadditionally suffers from a lack of chemical stability, which causesrusting. The presence of rust in pipes often gives rise to an unpleasantodor in the water.

[0004] In order to overcome these drawbacks, pipes are now made ofsynthetic thermoplastic resins such as polyvinyl chloride (PVC). WhilePVC provides significant benefits such as low weight, adequate hardnessand impact resistance, it suffers from drawbacks such as the lack ofheat and pressure stability. In order to improve heat stability, PatentNo. Hei 8-276549 teaches a multilayered fiber reinforced pipe having afirst layer formed from fiber-reinforced PVC, a second layer formed fromeither an acrylic resin or PVC containing a dispersed acrylic rubber anda third layer formed from acrylic resin laminated onto the outside ofthe first layer. However, differences in thermal expansion between thedifferent layers due to ambient temperature fluctuations often causethem to peel apart. Additionally PVC suffers from a lack of chemicalstability, which can give rise to the presence of chlorine, which may beundesirable. Plasticizers utilized in PVC such as pthalic acid ester andnonyl phenol may leach into the soil from embedded pipes, contributingto environmental issues. Thus, despite some of the advantages of PVCover steel, there remains a need for improved low weight, impactresistant and environmentally friendly piping for transmitting water andother fluids.

SUMMARY

[0005] A heat resistant pipe is formed from a composition comprisingpolyphenylene ether resin and polystyrene resin. Pipes made from thiscomposition possess superior thermal and pressure resistance. Theirimpact resistance and thermal expansion characteristics permit them tobe utilized advantageously in all environments and during all seasonswith little risk of failure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0006] It has been unexpectedly discovered that a composition comprisingpolyphenylene ether resin and polystyrene resin can be used toadvantageously mold pipes for the transmission and distribution of waterand other fluids. This pipe offers advantages of being able to transmitwater or other fluids at elevated temperatures of 80° C., withoutundergoing any warpage or distortion. The pipe, because of its hightemperature stability, can also be used through day and night during allseasons of the year without risk of damage to its dimensions.Additionally, because of the chemical stability of the molded pipe, thewater does not become contaminated with impurities.

[0007] The polyphenylene ether resins used in compositions generallycomprise a plurality of aryloxy repeating units preferably with at least50 repeating units of Formula (I)

[0008] wherein in each of said units independently, each of R1, R2, R3and R4 are hydrogen, halogen, hydrocarbon radical, substitutedhydrocarbon radical, alkoxy radical, cyano radical, phenoxy radical, ornitro radical and n is an integer showing the degree of polymerization.Non-limiting examples of substituents R1, R2, R3 and R4 in the formula(I) above are chlorine, bromine, iodine, methyl, ethyl, propyl, allyl,phenyl, benzyl, methyl benzyl, chloro methyl, bromo methyl, cyano ethyl,cyano, methoxy, ethoxy, phenoxy, nitro and combinations comprising atleast one of the foregoing substituents. Suitable but non-limitingexamples of polyphenylene ether resins that can be used in the pipe arepoly(2,6-dimethyl-1,4-phenylene)ether,poly(2,6-di-ethyl-1,4-phenylene)ether,poly(2-methyl-6-ethyl-1,4-phenylene)ether,poly(2-methyl-6-propyl-1,4-phenylene)ether,poly(2,6-di-propyl-1,4-phenylene)ether,poly(2-ethyl-6-propyl-1,4-phenylene)ether,poly(2,6-di-methoxy-1,4-phenylene)ether,poly(2,6-di-chloromethyl-1,4-phenylene)ether, poly(2,6-di-bromomethyl-1,4-phenylene)ether, poly(2,6-di-phenyl-1,4-phenylene)ether,poly(2,6-di-tolyl-1,4-phenylene)ether,poly(2,6-di-chloro-1,4-phenylene)ether,poly(2,6-di-benzyl-1,4-phenylene)ether,poly(2,5-di-methyl-1,4-phenylene)ether and combinations comprising atleast one of the foregoing polyphenylene ether resins. A preferredpolyphenylene ether resin is one wherein R1 and R2 in the formula (I)are alkyl radicals having 1 to 4 carbon atoms, R3 and R4 are hydrogenand wherein the degree of polymerization ‘n’ is about 50.

[0009] The polyphenylene ether resin may be either a homopolymer or acopolymer. Suitable copolymers include random copolymers containing2,6-dimethyl-1,4-phenylene ether units and 2,3,6-trimethyl-1,4-phenyleneether units. Other suitable copolymers are those wherein a styrenicpolymer is grafted onto a polyphenylene ether backbone. Examples ofstyrenic polymers, which can be grafted on to the polyphenylene etherbackbone, are polystyrene, α-methyl polystyrene, homopolymers ofvinyltoluene, homopolymers of chloro-styrene, and combinationscomprising at least one of the foregoing alkenyl aromatics. There is noparticular restriction to the viscosity of the polyphenylene ether resinused in the molded pipes, however, a preferred intrinsic viscosity is inan amount of about 0.1 to about 0.5 deciliters/gram (dl/g) when measuredin chloroform at 25° C.

[0010] The term “polystyrene resin” as used herein includes polymers,which contain at least 25% by weight of structural units derived from amonomer of the formula (II)

[0011] wherein R5 is a hydrogen or an alkyl radical having from 1 to 4carbon atoms; Z¹ is a halogen or an alkyl having from about 1 to about 4carbon atoms and p is an integer from 0 to about 5. The polystyreneresins are generally homopolymers of styrene (homo polystyrene)including syndiotactic polystyrene, which has a syndiotactic content ofgreater than 50 mole % as determined by nuclear magnetic resonance.

[0012] Copolymers of styrene may also be used in the pipes. Examples ofstyrenic monomers that may be copolymerized with styrene to formpolystyrene copolymers are p-methyl styrene, α-methyl styrene,α-methyl-p-methyl styrene, chlorostyrene, bromostyrene, and combinationscomprising at least one for the foregoing styrenic monomers. Otherpolymers which may be copolymerized with the polystyrene includepolybutadiene, polyisoprene, butyl rubber, ethylene-propylene dienemonomer (EPDM), ethylene-propylene copolymer, natural rubber, mixture ofnatural rubber with epichlorohydrin or a synthetic rubber containingstyrene or modified styrene, copolymers of natural rubber with asynthetic elastomer, styrene-acrylonitrile copolymer (SAN),styrene-butadiene copolymer (SBR), styrene-maleic anhydride copolymer,acrylonitrile-butadiene-styrene copolymer (ABS) and combinationscomprising at least one of the foregoing polymers. The preferredpolystyrene resin is homo polystyrene, syndiotactic polystyrene orrubber reinforced high impact polystyrene.

[0013] It is envisioned that recycled polystyrene resin recovered frommoldings or from foam can be used in the pipes. The recycled polystyreneresin may contain flame retardant additives if so desired. In addition,the polystyrene resin may be recovered from polystyrene moldings havinga surface, which coated or plated with a metal.

[0014] The weight average molecular weight of the polystyrene resin usedin the pipe is preferably greater than or equal to about 30,000 g/mole,more preferably greater than or equal to about 50,000 g/mole. It isgenerally desirable to vary the amount of polyphenylene ether resin fromabout 5 wt % to about 95 wt % based on the total weight of thecomposition. Similarly, it is generally desirable to vary thepolystyrene resin from about 5 wt % to about 95 wt % based on totalweight of the composition. A blend of polyphenylene ether resin andpolystyrene resin having the above detailed characteristics respectivelywill display excellent thermal resistance, mechanical strength,flowability, and dimensional stability.

[0015] Other additives may optionally be added to the composition. Theseinclude at least one type selected from the group consisting of arubbery impact modifier, fibrous filler, non-fibrous filler, olefinicpolymer, alicyclic saturated hydrocarbon resins, higher-grade fatty acidesters, waxes such as low molecular weight polyethylene and montan wax,petroleum variety hydrocarbons, fluoro polymers such aspolytetrafluoroethylene, antistatic agents such as sulfonic acid orpolyoxyalkylene glycols such as polyethylene glycol or polypropyleneglycol, ultraviolet (UV) absorbers such as compounds containing hinderedamine group, benzotriazole group, benzophenone group, epoxy group andcombinations comprising at least one of the foregoing UV absorberspigments.

[0016] Impact modifiers may also be used in the composition. The impactmodifier may be present as a homopolymer or a copolymer. In general itis desirable for the impact modifier to comprise at least one rubberycomponent having a glass transition temperature of greater than −100° C.and less than 50° C. Examples of such rubbery components arepolyisoprene, polybutadiene, polyolefins, polyacrylics, polyesters andthe like. The preferred impact modifiers are those, which containpolybutadiene such as styrene-butadiene rubber copolymerized withstyrene or hydrogenated styrene.

[0017] Impact modifiers comprising three polymers wherein one polymerhas as an acid component may also be used. Non-limiting examples areacrylic acid-butadiene-styrene copolymer, carbonicacid-butadiene-styrene copolymer or an acid compound containing carbonicacid anhydride-butadiene-styrene copolymer. Impact modifiers having arubbery component that comprises polyolefins such as ethylene orpropylene can also be used. Copolymers of ethylene and propylene canalso be used. Rubbery components such as a polyolefin containing an acidmodified component such as butadiene or a reactive epoxy functionalitymay also be used.

[0018] Fibrous fillers having aspect ratios from 2 to 1000 may be usedto impart strength to the composition. Noon-limiting examples of suchfibers are glass fibers, hollow glass fibers, carbon fibers, hollowcarbon fibers, titanium oxide whiskers, and warstonite. Non-fibrousfillers may also be utilized to impart strength and dimensionalstability to the pipe. Such fillers may exist is in the form ofplatelets, particles which may be crystalline or amorphous. Non-limitingexamples of such non-fibrous fillers are talc, clay, silica, glassflakes, glass beads, hollow filler etc. Combinations of fibrous andnon-fibrous fillers may also be used. Impact modifiers may generally beused in the pipe composition in an amount of up to about 7 wt % based onthe total weight of the composition.

[0019] In addition to being added as impact modifiers, polyolefins maybe added to modify the chemical resistance characteristics and moldrelease characteristics of the composition. Homo polymers such aspolyethylene, polypropylene, polybutene can be used either separately orin combination. Polyethylene can be added as high density polyethylene(HDPE), low density polyethylene (LDPE) or branched polyethylene.Polyolefins may also be used in copolymeric form with compoundscontaining carbonic acid radicals such as maleic acid or citric acid ortheir anhydrides, acid compounds containing acrylic acid radicals suchas acrylic acid ester, and the like, as well as combinations comprisingat least one of the foregoing.

[0020] Alicyclic, saturated hydrocarbon resins such as those availablefrom hydrogenation of aromatic hydrocarbon resin, for example generally,C9 hydrocarbon resin, C5/C9 hydrocarbon resin, indene-chroman resin,vinyl aromatic resin, terpene-vinyl aromatic resin and the like may alsobe used. With respect to the terpene variety, terpene resins formed byusing α-pinene, β-pinene, and diterpenes as the raw material ispreferred. Terpene denatured by aromatic hydrocarbon (phenol, bisphenolA, and the like) or hydrogen-saturated terpenes, and the like are alsouseful. With regards to the petroleum hydrocarbons, a liquid fraction ofpetroleum fraction is appropriate for use. Similarly with regards to thearomatic hydrocarbon petroleum resin, aromatic hydrocarbon fractionpolymer represented by C9 carbon variety is used. The hydrogen additionratio is desired to be high, preferably at least about 30%. If thequantity of aromatic component is greater, then desirable properties maybe lost.

[0021] Thermal stabilizers, which increase the thermal stability of thecomposition, may also be added. Such compounds include phosphitestabilization agents, epoxy compounds, beta-diketone, inorganicstabilizers such as perchloric acid salts, talc, zeolite and the like,as well as combinations comprising at least one of the foregoing thermalstabilizers. Preferred phosphite stabilization agents are tri alkylphosphite, alkyl aryl phosphite, tri aryl phosphite and combinationscomprising at least one of the foregoing phosphite stabilization agents.Thermal stabilizers may be added in quantities of greater than or equalto about 0.01, preferably greater than or equal to about 0.1 parts byweight based on 100 parts of weight of polyphenylene ether resin andpolystyrene resin. It is also generally desirable to add thermalstabilizers in quantities of less than or equal to about 70, preferablyless than or equal to about 50 parts by weight based on 100 parts ofweight of polyphenylene ether resin and polystyrene resin.

[0022] Flame retardants such as phosphorus compounds, siliconecompounds, metal salts and combinations comprising at least one of theforegoing flame retardants may also be used. Flame retardants may beadded in quantities of about 0.01 to about 50 parts by weight based on100 parts of weight of polyphenylene ether resin and polystyrene resin.Within this range it is preferable to use an amount of greater than orequal to about 0.1, more preferably greater than or equal to about 3,and most preferably greater than or equal to about 5 parts by weightbased on 100 parts of weight of polyphenylene ether resin andpolystyrene resin. Within this range, it is also generally desirable toadd thermal stabilizers in quantities of less than or equal to about 30parts by weight based on 100 parts of weight of polyphenylene etherresin and polystyrene resin.

[0023] Drip prevention agents such as those that prevent dripping duringcombustion, may also be utilized. Polytetrafluoroethylene is preferredas a drip prevention agent because of its ability to form fibrils in thecomposition. Other drip prevention agents, which can form fibrils, arealso preferred. Drip prevention agents may be added in quantities ofabout 0.01 to about 5 parts by weight based on 100 parts of weight ofpolyphenylene ether resin and polystyrene resin. Within this range it ispreferable to use the drip prevention agent in an amount of greater thanor equal to about 0.05 by weight based on 100 parts of weight ofpolyphenylene ether resin and polystyrene resin. Within this range, itis also generally desirable to add the drip prevention agents inquantities of less than or equal to about 3 parts by weight based on 100parts of weight of polyphenylene ether resin and polystyrene resin.

[0024] The polyphenylene ether resin and the polystyrene resin alongwith other desired additives may be melt blended and subsequently moldedinto a pipe. Melt blending operations are generally carried out in anextruder, ball mixer, roll mill, buss kneader and the like. During themelt blending operation, a small quantity of solvent may be added to themelt to facilitate processing if desired. During melt blending, thevarious components such as the polyphenylene ether, polystyrene and theother additives may be added simultaneously or sequentially if desired.

[0025] In one embodiment, in one manner of proceeding, the melt blendingof the polyphenylene ether, polystyrene and other additives may becompounded in an extruder by adding the components simultaneously at thethroat or sequentially through different feeders located at differentpositions along the barrel of the extruder. The extrudate emanating fromthe extruder may be either fed directly to a molding machine or cooledand converted into pellets, powder, and the like for use in a futuremolding operation.

[0026] The pipe may be molded from pellets, powder, and the like bymethods such as injection molding, extrusion molding, blow molding,vacuum forming, and any other molding operations known in the art.Alternatively, the pipe may be molded by feeding the components such asthe polyphenylene ether resin, polystyrene resin, and additives directlyinto the molding machine, where the components may be mixed immediatelyprior to molding. Both straight pipe sections as well as pipe joints maybe molded. Extrusion molding is generally preferred for straightsections while for injection molding is preferred for molding joints.

[0027] While pipe diameter, wall thicknesses, and shape may be chosen asdesired, a preferred wall thickness is from about 2.0 to about 10millimeters (mm). Pipe shapes may vary from cylindrical to quadrilateralto hexagonal, with cylindrical shapes generally being preferred.

[0028] Pipes made from the above composition may also be constructed inmulti-layered or laminated form comprising at least two layers.Multilayered pipes may be constructed utilizing as many layers as may bedesired so long as they are thermally stable and have water proofproperties. When a pipe has two or more layers, it is desirable that atleast one layer be constructed from the composition comprisingpolyphenylene ether resin and polystyrene resin.

[0029] Pipes made for water transmission and distribution, from theabove-described composition display thermal stability, strength andability to withstand high pressures in measures similar to PVC pipeswithout any of the drawbacks associated with PVC. For example, theoutstanding thermal stability of the composition as reflected in a V-cutsoftening point test measured as per JIS K7206, is more than 80° C.Similarly a test plate cut from the pipe composition has a tensilestrength greater than about 350 kgf/cm² at 15° C. and greater than about120 kgf/cm² at 90° C. Additionally because of its chemical stability,the pipe does not release any chlorine into the water and can berecycled for further use.

[0030] The excellent ability of the pipe composition to provide pipesthat can withstand high pressures can be seen in the water pressure testand the internal pressure creep test where water leakage does not occur.Further no cracks and fissures were seen in the flatness test, whichindicates the excellent pressure resistance characteristics of thecomposition. Pipes made from the above-described composition are alsoadvantageous in that they do not contain components such as lead, whichmay be transmitted by the water. Further other detrimental factors suchas increase in muddiness, color change, odor absorption, loss of taste,and the like, normally associated with steel pipes does not occur.Additionally, since the pipe does not contain any PVC, chlorine does notget into the water from the pipe. Because to the excellent thermalstability and chemical characteristics of the pipe composition,potassium permanganate normally used to purify drinking water may beused in lower quantities.

[0031] The present invention has been explained below in further detailwith non-limiting examples. However, the present invention is notrestricted to these practical examples.

EXAMPLES

[0032] The polyphenylene ether resin used in the examples waspoly(2,6-di methyl-1,4-phenylene)ether obtained from GE Plastics Co.(Japan) having an intrinsic viscosity of 0.46 dl/g when measured inchloroform at 25° C. TOPOLEX 870ST, a high impact polystyrenecommercially available from Japan Polystyrene Co. Ltd, was also used.Triphenyl phosphate (TPP), commercially available from Daihatsu ChemicalIndustries Ltd. was used as a flame retarding agent. Adegastab MK2112, aphosphate stabilizer commercially available from Asahi Electro-ChemicalIndustries, was used as thermal stabilizer. Kraton G-1651, comprisinghydrogenated styrene-butadiene copolymer commercially available fromShell Chemical Co., was used as the impact modifier.

[0033] Other additives such as NUC 6570, a denatured ethylene copolymercommercially available from Japan Uniker Co. Ltd was also used.

[0034] Table 1 shows the details of the composition. The composition wasextruded using a biaxial extrusion-kneading machine with the barreltemperature set at about 270° C. to about 280° C. and a screw speed of200 rpm. The extruded strand was the pelletized. The pellets were thenextruded into a water distribution cylindrical pipe having externaldiameter of 32 mm, thickness of 3.5 mm and total length of 4 meters in auniaxial extrusion machine. The extrusion conditions are shown in Table2. TABLE 1 Practical Practical Practical Comparative Composition example1 example 2 example 3 example Polyphenylene ether 44 57 30 36 resin(phr) Polystyrene resin (phr) 56 43 70 64 Flame retardant (phr) — 5 — —Impact modifier (phr) — — — 7 Thermal Stabilizer 0.1 0.1 0.1 0.1 (phr)Others (phr) — — — 3 Evaluation of molded product Tensile strength 540570 480 440 (23° C.) (Kg/cm²) Tensile strength 380 400 250 210 (23° C.)(Kg/cm²) Water pressure test No water No water No water No water (Visualjudgment) leakage leakage leakage leakage High temperature No water Nowater No water No water intemal leakage leakage leakage leakage pressurecreep test Flatness test Cracks Cracks Cracks Cracks absent absentabsent absent V cut softening 152 157 135 126 temperature test (° C.)Dissolution test Passed Passed Passed Passed Muddiness (passed if lessthan 0.5 degree) Degree of color Passed Passed Passed Passed (passed ifless than 1 degree) Consumption of Less than Less than Less than Lessthan potassium 2 mg 2 mg 2 mg 2 mg permanganate* Lead** Less than Lessthan Less than Less than 0.1 mg 0.1 mg 0.1 mg 0.1 mg Reduced quantity ofLess than Less than Less than Less than residual chlorine*** 1 mg 1 mg 1mg 1 mg Abnormal odor and Absent Absent Absent Absent taste

[0035] TABLE 2 Practical Practical Practical Comparative Moldingtemperature example 1 example 2 example 3 example 1 Extrusion Zone 1190° C. 230° C. 215° C. 200° C. machine Zone 2 200° C. 240° C. 225° C.210° C. Zone 3 210° C. 250° C. 235° C. 220° C. Zone 4 220° C. 260° C.245° C. 230° C. Ad 220° C. 260° C. 245° C. 230° C. Die Die 1 220° C.260° C. 245° C. 230° C. part Die 2 220° C. 260° C. 245° C. 230° C. Die 3220° C. 260° C. 245° C. 230° C. Die 4 220° C. 260° C. 245° C. 230° C.Sizing part Sizing  60° C.  80° C.  60° C.  60° C. former Vacuum WaterIndustrial Industrial Industrial Industrial water tube spray water waterwater water

[0036] Tensile tests and thermal measurements were performed on theextruded pipe. Two sections of the extruded pipe as shown in FIG. 1 weretested for tensile strength as per JIS K6776. Thermal stability (Vsoftening point temperature) was also measured as per JIS K7206 at aload of 5 kgf (49N). The test material having a length of 10 mm, breadth10 mm, and thickness between 2.5 and 4.5 mm was cut from the pipe. Waterpressure tests were measured on a test plate (cut from the pipe) havinga length of more than 1000 mm as per JIS K6776 at a water pressure of 40kgf/cm² (3.92 MPa) applied for a time period of 1 minute at roomtemperature. After the removal of pressure, the plate was visuallyexamined for water leakage.

[0037] High temperature internal pressure creep tests were performed ona test plate having length of more than 500 mm (cut from the extrudedpipe) as per JIS K6776. The test consists of subjecting the plate to awater pressure of 15 kgf/cm² (1.47 MPa) for 1 hour at 90±2° C. After theremoval of pressure, the plate was visually examined for water leakage.

[0038] A flatness test was also performed wherein a circular test platehaving a length of more than 50 mm was cut from the extruded pipe as perJIS K6776 and was sandwiched between 2 flat plates and it was compressedat right angles to the direction of the pipe axis at a speed of 10±2 mmper minute till the external diameter of the pipe is reduced in ½. Thepipe was then visually examined for the presence of cracks and fissures.

[0039] Dissolution tests were performed on a section of pipe cut in aspecific size as per JIS K6776. The pipe section was then washed withhot water having temperature of 90±2° C. for 1 hour. After this, one endwas blocked with a plug containing polyethylene film after which thepipe section was filled with the test water. The test water comprisedlimewater added to refined water and the pH was regulated between 8.0and 7.5 by passing CO₂ through the water. Chlorine was then added to thetest water such that it contains approximately 2 ppm of free (liberated)residual chlorine following which the other end was plugged (corked) andit was kept undisturbed for 24 hours at normal temperature. After 24hours, muddiness, degree of color, quantity of consumption of potassiumpermanganate, quantity of lead, reduced quantity of residual chlorine ofthe test water were evaluated as per the JIS K6776 appendix. Materialshaving the same to be less than 1.0 were taken as having passed thetest. Smell and taste were evaluated as per functional tests.

[0040] As can be seen from the data of Table 1, the extruded pipe hasexcellent thermal stability and exhibits a good resistance to pressure.For example, it does not get damaged even if hot water havingtemperature in the vicinity of 80° C. is transmitted through it. Thepipe displays an excellent balance of mechanical properties such asstrength, impact resistance with thermal properties and chemicalproperties. It does not suffer from any damage to its dimensions,despite being subjected to the vagaries of the weather. Furthermore,impurities do not contaminate water transmitted through the pipe. Thispipe can therefore be used as a substitute for polyvinyl chloridepiping.

[0041] While the invention has been described with reference toexemplary embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention.

1. A heat resistant pipe formed from a composition comprising based onthe total weight of the composition: about 5 to about 95 wt %polyphenylene ether resin; and about 5 to about 95 wt % polystyreneresin.
 2. The pipe of claim 1, wherein the polyphenylene ether resin isselected from the group consisting ofpoly(2,6-dimethyl-1,4-phenylene)ether,poly(2,6di-ethyl-1,4-phenylene)ether,poly(2-methyl-6-ethyl-1,4-phenylene)ether,poly(2-methyl-6-propyl-1,4-phenylene)ether,poly(2,6-di-propyl-1,4-phenylene)ether,poly(2-ethyl-6-propyl-1,4-phenylene)ether,poly(2,6-di-methoxy-1,4-phenylene)ether,poly(2,6-di-chloromethyl-1,4-phenylene)ether, poly(2,6-di-bromomethyl-1,4-phenylene)ether, poly(2,6-di-phenyl-1,4-phenylene)ether,poly(2,6-di-tolyl-1,4-phenylene)ether,poly(2,6-di-chloro-1,4-phenylene)ether,poly(2,6-di-benzyl-1,4-phenylene)ether,poly(2,5-di-methyl-1,4-phenylene)ether and combinations comprising atleast one of the foregoing polyphenylene ether resins.
 3. The pipe ofclaim 1, wherein the polyphenylene ether resin has the structure shownin formula (I)

wherein R1 and R2 are alkyl radicals having 1 to 4 carbon atoms, R3 andR4 are hydrogen and wherein ‘n’ is about
 50. 4. The pipe of claim 1,wherein the polystyrene is selected from the group consisting of homopolystyrene, high impact polystyrene, and syndiotactic polystyrene. 5.The pipe of claim 1, wherein the polystyrene resin is derived from amonomer having the structure shown in formula (II)

wherein R5 is a hydrogen or an alkyl radical having from 1 to 4 carbonatoms; Z¹ is a halogen or an alkyl having from about 1 to about 4 carbonatoms and p is an integer from 0 to about
 5. 6. The pipe of claim 1,wherein the polystyrene resin is recycled resin.
 7. The pipe of claim 1,wherein the composition further comprises an impact modifier in anamount of up to about 7 wt %.
 8. The pipe of claim 1, further comprisingan additive selected from the group consisting of rubbery impactmodifier, fibrous filler, non-fibrous filler, olefinic polymer,alicyclic saturated hydrocarbon resins, higher-grade fatty acid esters,waxes, polyolefins, petroleum variety hydrocarbons, fluoro polymers,antistatic agents, ultraviolet absorbers, and combinations comprising atleast one of the foregoing additives.
 9. A heat resistant pipe formedfrom a composition comprising based on the total weight of thecomposition: about 5 to about 95 wt % polyphenylene ether resin; andabout 5 to about 95 wt % recycled polystyrene resin.
 10. The pipe ofclaim 9, wherein the further comprising an additive selected from thegroup consisting of rubbery impact modifier, fibrous filler, non-fibrousfiller, olefinic polymer, alicyclic saturated hydrocarbon resins,higher-grade fatty acid esters, waxes, polyolefins, petroleum varietyhydrocarbons, fluoro polymers, antistatic agents, ultraviolet absorbers,and combinations comprising at least one of the foregoing additives. 11.The method of forming a pipe comprises: melt blending a compositioncomprising about 5 to about 95 wt % polyphenylene ether resin and about5 to about 95 wt % polystyrene resin; and molding the melt blend. 12.The method of claim 11, wherein the melt blending is carried out in amelt blender selected from the group consisting of an extruder, busskneader, roll mill, ball mill, and combinations comprising at least oneof the foregoing melt blender.
 13. The method of claim 11, wherein themolding is accomplished by injection molding, extrusion molding, blowmolding, or vacuum forming.
 14. The method of claim 11, wherein thecomposition further comprises an additive selected from the groupconsisting of rubbery impact modifier, fibrous filler, non-fibrousfiller, olefinic polymer, alicyclic saturated hydrocarbon resins,higher-grade fatty acid esters, waxes, polyolefins, petroleum varietyhydrocarbons, fluoro polymers, antistatic agents, ultraviolet absorbers,and combinations comprising at least one of the foregoing additives.